In some high-reliability computer applications, and in various other situations, small hydraulic cooling systems are used. The couplings for such systems should be of the "no-spill" type--that is, no fluid should be lost when they are disconnected--but they may typically have diameters of only one-half inch or less. Their small size presents special design problems, foremost among which is that a greater simplicity than usual is required for the manufacture and assembly of couplings with many tiny parts is obviously time and labor consuming.
Yet these couplings must often have design features found in full-size devices. For example, hydraulic cooling systems for computers may incorporate so-called "cold plates", flat panels of thin metal for heat exchange in the coolant. Since they are subject to rupture when excessive heat causes pressure buildup, it is desirable to provide a relief valve in the coupler half. The usual relief valve arrangement, however, involves a separate popper valve and spring, together with various small retainers and seals. A need therefore exists for a simpler design which minimizes the number of extra parts required for the relief valve. It is also an advantage if the coupling can be connected even when the halves are presented to each other not exactly aligned.